Posts with the tag "Secret Intelligence Service"

British intelligence services experimented with using semen as an invisible ink to write top-secret letters, it has been disclosed.

A diary entry belonging to a senior member of the Secret Intelligence Service (MI6) has revealed that during the First World War it was discovered that the bodily fluid could act as an effective invisible ink.

In June 1915, Walter Kirke, deputy head of military intelligence at GHQ France, wrote in his diary that Mansfield Cumming, the first chief (or C) of the SIS was “making enquiries for invisible inks at the London University”.

In October he noted that he “heard from C that the best invisible ink is semen”, which did not react to the main methods of detection. Furthermore it had the advantage of being readily available.

Apparently the agent was later laughed out of his department. And another had to be reminded to use fresh supplies of the ink “when correspondents began noticing an unusual smell.” M6 just became a little bit less badass.